The present invention relates to a controller of a direct injection engine and, more particularly, to a direct injection engine controller for controlling an opening of a swirl control valve for imparting a swirl to the intake air supplied in the direct injection engine.
Hitherto, for a direct injection engine, it is necessary to effect lean combustion at an air fuel ratio A/F of 40 or more, therefore, gas flow called swirl or tumble is imparted to the air in the combustion chamber of each cylinder. Although there are various means for imparting such gas flow, in general, a suitable gas flow is produced by a combination of a shape of suction pipe and a swirl control valve.
One example of conventional such technique for producing and controlling a swirl using a swirl control valve is disclosed in JP A 7-293260. The technique disclosed in JP A 7-293260, in a fuel injection type engine in which a combustion type (combustion state) is switched to stratified combustion or homogeneous combustion by controlling a fuel injection valve on the basis of operational conditions of the engine, is to improve the combustion condition by controlling the swirl control valve according to the above-mentioned switching of the combustion types to change a producing state of the swirl. Concretely, one of the above-mentioned stratified combustion and homogeneous combustion is selected by controlling so as to change an injection state of the fuel injection valve on the basis of the number of revolutions of an engine and an engine load, and when the stratified combustion and the homogeneous combustion except for an opening position near to a full opening of a throttle valve are selected, the swirl control valve is controlled to close, and when the homogeneous combustion at the opening position near to a full opening of the throttle valve is selected, the swirl control valve is controlled to open.